Formation of Rh islands on Pd-supported α-Fe2O3 (0001)

A rhodium ultra-thin film was deposited on a Pd-supported alpha-Fe2O3 (0001) film by molecular beam epitaxy (MBE). The surface atomic and electronic structures were studied using X-ray photoelectron diffraction (XPD), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). For an oxide thin film (similar to 16.5 angstrom), an ordered (root 3 x root 3)R30 degrees structure was observed. The multiple scattering calculation approach combined with a genetic algorithm for surface structure optimization was used to investigate precisely the atomic structure of the oxide support as well as the Rh nanoislands or nanoparticles (NPs). Rh exhibited 3D growth on an alpha-Fe2O3 thin film forming NPs with a lattice constant expanded by 5.26% relative to the Rh bulk value. The coexistence of 60 degrees rotated domains and also evidence of Fe termination at the surface of alpha-Fe2O3 were observed.